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Java將矩形添加到ArrayList中,然后繪制它們

[英]Java add rectangles to ArrayList and then draw them

我真的很需要你們的幫助。 我嘗試將矩形添加到ArrayList中,然后遍歷列表以繪制所有矩形。 我不確定是否使用了正確的方法,但是到目前為止,這是我的代碼。

編輯:代碼不會繪制我添加到ArrayList的矩形。 我什至不知道是否以正確的方式添加它們,或者以正確的方式通過for循環訪問它們。

在TestProgram中

import java.awt.BorderLayout;
import java.awt.Graphics;
import java.util.ArrayList;
import javax.swing.JFrame;


public class TestProgram extends JFrame {
    private ShapeRectangle rectangle;
    public ArrayList<Shapes> list = new ArrayList<Shapes>();


    public TestProgram(String title) {
        super(title);
        setLayout(new BorderLayout());
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setLocationRelativeTo(null);
        initComponents();
        setSize(500, 700);
        setVisible(true);
  }

    private void initComponents() {
        rectangle = new ShapeRectangle();    
        add(rectangle, BorderLayout.CENTER);

        list.add(rectangle);        
        Graphics g = getGraphics();
        for (int i = 0; i < list.size(); i++) {
            rectangle.draw(g);
        }
  }

    public static void main(String args[]) {
        new TestProgram("Drawing program");
    }
}

在ShapeRectangles類中:

import java.awt.Graphics;

public class ShapeRectangle extends Shapes {

    public ShapeRectangle() {}    

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponents(g);
        draw(g);        
    }

    @Override
    public void draw(Graphics g) {
       g.drawLine(20,20,60,60);
       g.drawLine(130,30,80,11);
       g.drawRect(200,30,20,140);        
   }
}

在Shapes類中:

import java.awt.Graphics;
import javax.swing.JPanel;

public abstract class Shapes extends JPanel {

    abstract public void draw(Graphics g); 

}

不要使Shapes成為JPanel 還要取出其paintComponent方法。

而是有一個JPanel類,它是主繪圖表面。 List<Shapes>保留在類中。 遍歷該類的paintComponent方法中的列表,調用每個Shapes的draw方法

class DrawingPanel extends JPanel {
    List<Shapes> shapes;
    // add shapes

    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        for (Shapes shape: shapes) {
            shape.draw(g);
        }
    }
}

然后只需將該面板添加到框架中即可。

請記住,所有繪畫都應通過傳遞到paintComponent方法中的Graphics上下文完成。 我們不使用getGraphics進行自定義繪畫。

另外,您可能需要在Shapes類中存儲一些狀態,以便可以更改x / y / width / height狀態。 現在,您正在為所有形狀使用相同的硬編碼值。

abstract class Shapes {
    int x, y;
    public Shapes(int x, int y) {
        this.x = x; this.y = y;
    }
    protected abstract void draw(Graphics g);
}
class RectangleShape extends Shape {
    int width, height;
    public RectangleShape(int x, int y, int width, int height) {
        super(x, y);
        this.width = width; this.height = height;
    }
    @Override   
    public void draw(Graphics g) {
        g.fillRect(x, y, width, height);
    }
}

查看帶有動畫的更復雜對象完整示例

這很不好,您要么想要將其添加為具有絕對定位的組件,要么想要繪制它,請選擇一個。

this.add(rectangle, BorderLayout.CENTER); // Add as component of the panel.
list.add(rectangle);                      // Add as method of drawing on the panel.

后者會更好,因為您正在繪圖。 如果需要拖放,請將其作為子項添加,但將圖形添加到子項中。

更改矩形的坐標和大小后,可以在JFrame上調用repaint()來更新圖形。

繪制形狀

import java.awt.BorderLayout;
import java.awt.Graphics;
import java.util.ArrayList;

import javax.swing.JFrame;
import javax.swing.SwingUtilities;

public class DrawShapes extends JFrame {
    public ArrayList<Shape> shapeList = new ArrayList<Shape>();

    public DrawShapes(String title) {
        super(title);

        this.setLayout(new BorderLayout());
        this.setDefaultCloseOperation(EXIT_ON_CLOSE);
        this.setSize(500, 700);
        this.setLocationRelativeTo(null);

        this.initComponents();
    }

    private void initComponents() {
        shapeList.add(new RectangleShape(20, 20, 60, 60));
        shapeList.add(new RectangleShape(130, 30, 80, 11));
        shapeList.add(new RectangleShape(200, 30, 20, 140));
    }

    @Override
    public void paint(Graphics g) {
        for (Shape s : shapeList) {
            s.draw(g);
        }
    }

    public static void main(String args[]) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                DrawShapes d = new DrawShapes("Drawing program");
                d.setVisible(true);
            }
        });
    }
}

矩形形狀

import java.awt.Graphics;

public class RectangleShape extends Shape {
    public RectangleShape(int x, int y, int width, int height) {
        super(x, y, width, height);
    }

    public RectangleShape() {
        super();
    }

    @Override
    public void draw(Graphics g) {
        g.drawRect(getX(), getY(), getWidth(), getHeight());
    }
}

形狀

import java.awt.Graphics;

public abstract class Shape {
    private int x;
    private int y;
    private int width;
    private int height;

    public Shape() {
        this(0, 0, 1, 1);
    }

    public Shape(int x, int y, int width, int height) {
        this.x = x;
        this.y = y;
        this.width = width;
        this.height = height;
    }

    public abstract void draw(Graphics g);

    public int getX() {
        return x;
    }

    public void setX(int x) {
        this.x = x;
    }

    public int getY() {
        return y;
    }

    public void setY(int y) {
        this.y = y;
    }

    public int getWidth() {
        return width;
    }

    public void setWidth(int width) {
        this.width = width;
    }

    public int getHeight() {
        return height;
    }

    public void setHeight(int height) {
        this.height = height;
    }
}

首先看一下2D圖形 ,特別是使用幾何圖形

2D圖形API定義了Shape API,該API除其他外還包括Rectangle

例如...

在此處輸入圖片說明

import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class TestRectangles {

    public static void main(String[] args) {
        new TestRectangles();
    }

    public TestRectangles() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        private List<Rectangle> rectangles;

        public TestPane() {
            rectangles = new ArrayList<>(25);
            Random ran = new Random();

            for (int index = 0; index < 10; index++) {
                int x = ran.nextInt(200 - 10);
                int y = ran.nextInt(200 - 10);
                int width = ran.nextInt(200 - x);
                int height = ran.nextInt(200 - y);
                rectangles.add(new Rectangle(
                        x, 
                        y, 
                        width, 
                        height));
            }
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(200, 200);
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g.create();
            for (Rectangle rect : rectangles) {
                g2d.draw(rect);
            }
            g2d.dispose();
        }

    }

}

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